just bought this car.its a 89 with a 91 305 ho motor with vortec heads,eldlejunk 600cfm carb,edlejunk headers and a 700r4 with shift kit 3500 stall nonlock tc tcc been bypassed i was tol
the problem is when i let off the gas or brake the car stallsnot all the time just once out of every 5-10 times i let off the gass or break,being as ive never delt with a car with stright carb and no chip i dont know what it could be,ive checked the brake booster check valve,also idles vary vary quietly almost too quiet,but vibrates alot

 

I'd start with basics - what rpm is the idle set at? What's the base timing set to? Check for vacuum leaks. What fuel pressure? Using stock intank pump or mechanical pump or aftermarket electric? If intank pump, did they use a RETURN style regulator? If aftermarket or mechnanical pump, did they remove the intank pump? We need alot more info here.

 

Sticky at top of carb forum that has a lot of good info on edelbrock carbs.

 

guy gave me car with timing 14 degrees off that was problem